Republican presidential frontrunner Mitt Romney has said that Iran will acquire a nuclear bomb if President Obama is re-elected.

It's pretty straightforward in my view. If Barack Obama is re-elected, Iran will have a nuclear weapon and the world will change if that's the case, AFP quoted Romney as saying to his supporters in Atlanta, Georgia, Sunday.

This is a president who has failed to put into place crippling sanctions against Iran. And (has failed to communicate) that it's unacceptable to America for Iran to have a nuclear weapon, he said.

Romney's statement closely follows Obama's stern warning to Iran saying that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say.

In the light of Israeli Prime Minister Benjamin Netanyahu's visit to Washington to discuss strategies regarding Iran's allegedly clandestine nuclear weapons program, Obama made it clear that the U.S. would strive to protect its ally Israel, though he would persuade the Jewish state to postpone its war plans.

In an interview held last week, Obama said that the U.S. has Israel's back and that it would initiate a military strike on Iran if Tehran failed to pull the plug on its nuclear arms program.

I think that the Israeli government recognizes that, as president of the United States, I don't bluff, Obama told journalist Jeffrey Goldberg of The Atlantic. I also don't, as a matter of sound policy, go around advertising exactly what our intentions are. But I think both the Iranian and the Israeli governments recognize that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say.

Obama said military action would only be the final option while all options are on the table on how to handle the Iran situation.

The Obama administration wants Israel to wait a few more months since that would provide enough time to see if international sanctions and penalties had the desired effect on Iran.

Without in any way being under an illusion about Iranian intentions, without in any way being naive about the nature of that regime, they are self-interested, Obama said.

It is possible for them to make a strategic calculation that, at minimum, pushes much further to the right whatever potential breakout capacity they may have, and that may turn out to be the best decision for Israel's security.

Criticizing Obama's Iranian policy, Romney said that he would have those military options, and would take those crippling sanctions and put them into place.

I will speak out to the Iranian people of the peril of them becoming nuclear, Romney said.

Iran situation is expected to dominate the talks between Obama and Netanyahu scheduled at the White House Oval Office Monday.